Method for encapsulating a semiconductor utilizing an epoxy resin and an onium salt compound

Abstract

A method of encapsulating a semiconductor comprising encapsulating a semiconductor in a curable epoxy resin composition comprising a liquid epoxy resin, an inorganic filler, an onium salt compound and an internal releasing agent, and substantially not containing a hardener, and then molding the above composition.

We claim: 
     
       1. A method of encapsulating a semiconductor, which comprises: encapsulating a semiconductor in a curable epoxy resin composition comprising: (A) a liquid epoxy resin or a curable liquid mixture comprising an epoxy resin and a diluent;   (B) an inorganic filler;   (C) an onium salt compound represented by the formula (I) or (II): ##STR3## wherein E represents sulfur, nitrogen or phosphorus; Ar represents an aromatic ring; when a is 2, the R a   1  s are the same or different and represent a substituted or unsubstituted monovalent hydrocarbon group, a hydroxyl group, an alkoxyl group, a nitro group, a cyano group or a halogen atom; R 2  and R 3  each represent a hydrogen atom or a methyl group; the R b   4  s are the same or different and represent a substituted or unsubstituted monovalent hydrocarbon group; R 5  represents a substituted or unsubstituted pyridinium group; a represents an integer of 0 to 2; and b represents 2 when E is sulfur or represents 3 when E is nitrogen or phosphorus; and   (D) an internal releasing agent,     and substantially not containing a hardener, and then molding the above composition.   
     
     
       2. The method according to claim 1, wherein molding is carried out by injection molding or transfer molding. 
     
     
       3. The method according to claim 1, wherein molding is carried out at 120° to 190° C. 
     
     
       4. A semiconductor device which comprises a semiconductor encapsulated by the method according to claim 1.